You can definitely tell which one's the AI, but if you weren't particularly paying attention on, say, a phone call (where you're used to bad audio quality anyway), you might not immediately notice.
I can't speak for anyone else but I would recognize that as software-generated instantaneously. It's unmistakable imo, and actually sounds significantly worse than, for example, these samples from Google's Tactotron 2 system: http://www.androidpolice.com/2017/12/28/googles-new-text-spe...
